Problem with PC crashing

hello fellow OCNers. i am running into a problem with my PC. every now and then i get random Crashes and i do not know why
i can run Prime 95 and it be fine but when something like valley is run it restarts before the benchmark starts. but i can "sometimes" game
my PSU is corsair HD 750 and my GPU is MSI HD 7870 at stock. and sometimes just browsing has caused it to crash

event view just shows error id 41 which is the pc shutting down forcefully

what could be my issue. i dont know what is really causing these crashes
my cpu is i5 2500k at 4.5 and im using latest AMD drivers 13.8 beta 2

sounds like your psu is no happy with the load
which explains the being able to run prime because it just uses the cpu and the gpu draws a much higher wattage
or could be your overclock is causing an instability when also running in cooperation with the gpu